title: Intact MDM2 E3 ligase activity is required for the cytosolic localization and function of β-arrestin2.
abstract: β-arrestins are well known for their roles in desensitization and sequestration of G protein-coupled receptors. Unlike β-arrestin1, β-arrestin2 exhibits a predominant cytoplasmic distribution at steady state. However, the mechanism and functional significance underlying the regulation of β-arrestin2 subcellular localization remains undefined. Here we report that the subcellular localization and function of β-arrestin2 is tightly regulated by Mdm2 E3 ligase activity. Inhibition of Mdm2 E3 ligase activity either by expressing Mdm2 RING finger mutants or using specific Mdm2 E3 ligase inhibitor is sufficient to stabilize the Mdm2/β-arrestin2 complex and cause abnormal nuclear localization of β-arrestin2. Next we demonstrate that lysine residues at position 11 and 12 of β-arrestin2 are required for the interaction between Mdm2 RING finger mutant H457S (Mdm2(H457S)) and β-arrestin2, mutation of which prevents Mdm2(H457S)/β-arrestin2 interaction and subsequent nuclear localization of β-arrestin2. Finally, β-arrestin2-dependent signalings, such as receptor internalization and extracellular signal-regulated protein kinase activation, are found to be impaired once the β-arrestin2 is sequestered in the nuclei by Mdm2(H457S). Our findings depict the essential role of Mdm2 E3 ligase activity in determining β-arrestin2 subcellular localization and corresponding signaling.
authors.affiliation: Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
authors.forename: Chenlei
authors.initials: C
authors.lastname: Yin
authors.forename: Ru
authors.initials: R
authors.lastname: Zhang
authors.forename: Yongyu
authors.initials: Y
authors.lastname: Xu
authors.forename: Qiuyan
authors.initials: Q
authors.lastname: Chen
authors.forename: Xin
authors.initials: X
authors.lastname: Xie
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D019390:Arrestins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus; D003593:Cytoplasm / Q000378:metabolism / Q000502:physiology; D003600:Cytosol / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D047468:Immunoprecipitation; D051379:Mice; D008856:Microscopy, Fluorescence; D009154:Mutation; D051736:Proto-Oncogene Proteins c-mdm2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D054829:RING Finger Domains / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology; D054875:Ubiquitination; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D000071557:beta-Arrestins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; D048049:Extracellular Signal-Regulated MAP Kinases